BACKGROUNDMedulloblastoma is an aggressive pediatric brain tumor with surgery and post-resection radiotherapy plus chemotherapy as the major type of treatment currently.METHODSA cohort of 52 medulloblastoma patients were treated in Taipei Medical University Hospital and Taipei Veterans General Hospital. Among them, 28 (53.85%) are male. The average age at presentation is 7.21 ± 4.15. Genome-wide RNA profiling were performed on fresh-frozen surgical samples. Tumor infiltrating immune cell percentages were inferred by the cibersort immune deconvolution algorithm.RESULTSA total of 13 leading genes, including DLL1, ASIC2, SLC22A17, TRPM3, RPS2P5 and KCNC3, were found to be significantly associated with overall survival (All P < 0.001). A risk score was constructed, which is indicative of overall survival (Hazard Ratio [HR] = 2.720, 95% confidence interval [CI] = 1.798 ~ 4.112, P < 0.001) and recurrence-free survival (HR = 1.645, CI = 1.337 ~ 2.025, P < 0.001). After adjustment of clinical factors, the score remained significantly associated with overall survival (HR = 2.781, CI = 1.762 ~ 4.390, P < 0.001) and recurrence-free survival (HR = 1.604, CI = 1.292 ~ 1.992, P < 0.001). The percentage of Natural Killer and T follicular helper (Tfh) cells were higher in patients with better overall survival (P = 0.046 and 0.001, respectively). Furthermore, the Tfh percentage is also positively associated with mutation burdens in the expressed exonic regions (P < 0.001).CONCLUSIONHigher mutation burdens are correlated with higher levels of tumor infiltrating Tfh cells, which is indicative of better post-surgery prognosis.